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FDSC 310 > 7 Cold Storage Systems > Flashcards

7 Cold Storage Systems Flashcards

1
Q

list examples of simple and complex systems

A

simple:

  • ventilated storage
  • regular atmosphere storage

complex

  • CA storage
  • hypobaric storage
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2
Q

what are considered complex controls?

A

control of several of these:

  • temp
  • RH
  • air velocity
  • air composition
  • insulation
  • refrigeration cap
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3
Q

what are some important factors to consider for picking a storage method?

A
  • requirements of different commodities
  • consolidating of produce with similar needs to save space
  • how temperature affects produce
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4
Q

temperature fluctuation should be ± ____°C

A

2

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5
Q

large temperature fluctuation leads to (increase/decrease) of quality

A

decrease

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6
Q

what happens if refrigeration capacity is undersized?

A
  • slow cooling
  • product warming
  • large temp fluctuations
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7
Q

what happens if refrigeration is oversized?

A

wasted captial

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8
Q

which is preferred? one large unit or several small units?

A

several small units

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9
Q

how do you decrease temperature fluctuation?

A

keeping room T close to refrigeration T

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10
Q

(larger/smaller) surface area leads to more efficient heat transfer

A

larger

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11
Q

a _____ rate of air flow is ideal

A

moderate; too high and it will desiccate, too low and it won’t transfer heat efficiently

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12
Q

how do you prevent heat gain?

A

insulation

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13
Q

name 3 storage techniques to maintain high RH

A

jacketed, filacell, fog spray

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14
Q

describe the fog spray storage system

A

moisture is directly added to air stream; can make use of sonication (exfoliation using sound)

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15
Q

proper air circulation depends on:

A
  • fan type and capacity
  • air delivery
  • package design
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16
Q

true or false: mass transfer is desirable

A

false. that’s water weight, and that decreases quality and sellable weight.

17
Q

air velocity is important for maintaining _____ and establishing _____ CA condition

A

temperature, homogeneous

18
Q

what happens in CA/MA storage?

A
  • prevent depletion of O2
  • prevent build-up of CO2 and ethylene

keep O2 at 2% (lower than normal)
keep CO2 at 5% (higher than normal)
remove ethylene

19
Q

name some building materials

A

concrete, masonary bricks, wood frame, steel frame

20
Q

name some insulating materials

A

fiberglass, polystyrene, polyurethane foam, urea formaldehyde

21
Q

what’s used as a vapor barrier/gas seal?

A

polyurethane

22
Q

what are the conventional refrigerated storage methods?

A

Jacketed and Filacell

23
Q

what are the CA storage methods?

A
  • CA generation and maintenance
  • membrane systems (marcellin, atmolysair)
  • hypobaric system
24
Q

what are the desirable effects of CA storage?

A
  • suppression of respiration rate
  • retardation of senescence
  • suppression of ethylene production
  • reduction in fruit sensitivity to ethylene
  • alleviation of physiological disorders
  • suppression of pathogen activity
  • insect control
25
Q

what are the undesirable effects of CA storage?

A
  • can promote other physiological disorders
  • induce irregular ripening
  • can favor development of fof flavors
  • can favor stimulation of sprouting and retardation of periderm formation in some roots and tubers
26
Q

what are the 2 aspects of CA/MA storage?

A

1) CA generation

2) CA maintenance

27
Q

how is CA generation achieved?

A
  • passive process - produce respiration

- active process - external means

28
Q

what are some oxygen control systems

A
  • recirculation/purge type
  • external gas generators (open flame burners, catalytic converters)
  • nitrogen generators (gas/liquid nitrogen cylinders and smit-oxydrain)
  • control is ventilation (addition of O2)
29
Q

what are some CO2 control systems?

A
  • gas cylinders

- control by scrubbers like hydrated lime, water, brine water, and activated carbon/molecular sieves

30
Q

what is lime?

A

CaOH2

31
Q

what are regular atmospheric concentrations of N, O and CO2?

A 
N = 79%
O = 21%
CO2 = trace
32
Q

what happens to CO2 in CA storage

A

allowed to increase to 6% by respiration the brought down to 5%

33
Q

what happens to O2 in CA storage?

A

allowed to decrease to 2.5% and restored to 3% by ventilation

34
Q

what is the role of N2 in CA storage?

A

mainly filler. ~92% at maintained O2 and CO2 levels.

FDSC 310 (11 decks)

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